ZHAO Jun-Hong, WANG Wei, LIU Hang
Department of Earth Sciences, China University of Geosciences (Wuhan), Wuhan 430074, China
Abstract: South China underwent complicated geological evolutions during the Neoproterozoic. It is characterized by amalgamation of the Yangtze and Cathaysia blocks along the Jiangnan Fold Belt and the subsequent formation of the Nanhua intracontinental rift basin. The Jiangnan Fold Belt is composed of sedimentary and volcanic rocks that experienced strong deformation and greenschist facies metamorphism. This belt was intruded by numerous 820Ma peraluminous granitic plutons. The Nanhua rift basin is filled with the Late Neoproterozoic strata which are overlaid unconformably on the granitic intrusions and the Jiangnan Fold Belt. In the past few decades, three models had been proposed, including the plume model, the plate-rift model and the arc model. Alternatively, based on systematic studies of sedimentary and igneous rocks in the region, we proposed a new model, the subduction-back-arc rift model (SBAR). This model can be summarized as follows: subduction of oceanic slab beneath the southeastern margin of the Yangtze Block began at 850Ma. The Early Neoproterozoic strata were deposited in the fore-arc setting; the assemblage of Yangtze and Cathaysia blocks occurred at 830Ma; the long term subduction beneath the northwestern margin of the Yangtze Block resulted in asthenosphere upwelling and back-arc spreading at its southeastern part, which is the key factor controlling generation of granite and formation of the Nanhua rift basin.
Keywords: Neoproterozoic evolution southeastern Yangtze Block South China
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Bulletin of Mineralogy, Petrology and Geochemistry Vol. 34, No.2, 2015, page 227-233